border-1px($color)
    position: relative
    &:after
        display: block
        position: absolute
        left: 0
        bottom: 0
        border-top: 1px solid $color
        content: ''
        width: 100%

bg-img($url)
    background-image url($url+'@2x.png')
    @media (-webkit-min-device-pixel-ratio:3),(min-device-pixel-ratio:3) {
        background-image url($url+'@3x.png')
    }

